/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.lee.util.xml;

import javax.xml.namespace.QName;
import javax.xml.stream.XMLStreamConstants;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.XMLStreamReader;

import com.lee.util.Assert;

/**
 * Abstract base class for {@code XMLStreamReader}s.
 *
 * @author Arjen Poutsma
 * @since 3.0
 */
abstract class AbstractXMLStreamReader implements XMLStreamReader {

    @Override
    public String getElementText() throws XMLStreamException {
        if (getEventType() != XMLStreamConstants.START_ELEMENT) { throw new XMLStreamException(
                "parser must be on START_ELEMENT to read next text", getLocation()); }
        int eventType = next();
        StringBuilder builder = new StringBuilder();
        while (eventType != XMLStreamConstants.END_ELEMENT) {
            if (eventType == XMLStreamConstants.CHARACTERS || eventType == XMLStreamConstants.CDATA
                    || eventType == XMLStreamConstants.SPACE || eventType == XMLStreamConstants.ENTITY_REFERENCE) {
                builder.append(getText());
            } else if (eventType == XMLStreamConstants.PROCESSING_INSTRUCTION
                    || eventType == XMLStreamConstants.COMMENT) {
                // skipping
            } else if (eventType == XMLStreamConstants.END_DOCUMENT) {
                throw new XMLStreamException("unexpected end of document when reading element text content",
                        getLocation());
            } else if (eventType == XMLStreamConstants.START_ELEMENT) {
                throw new XMLStreamException("element text content may not contain START_ELEMENT", getLocation());
            } else {
                throw new XMLStreamException("Unexpected event type " + eventType, getLocation());
            }
            eventType = next();
        }
        return builder.toString();
    }

    @Override
    public String getAttributeLocalName(int index) {
        return getAttributeName(index).getLocalPart();
    }

    @Override
    public String getAttributeNamespace(int index) {
        return getAttributeName(index).getNamespaceURI();
    }

    @Override
    public String getAttributePrefix(int index) {
        return getAttributeName(index).getPrefix();
    }

    @Override
    public String getNamespaceURI() {
        int eventType = getEventType();
        if (eventType == XMLStreamConstants.START_ELEMENT || eventType == XMLStreamConstants.END_ELEMENT) {
            return getName().getNamespaceURI();
        } else {
            throw new IllegalStateException("parser must be on START_ELEMENT or END_ELEMENT state");
        }
    }

    @Override
    public String getNamespaceURI(String prefix) {
        Assert.notNull(prefix, "No prefix given");
        return getNamespaceContext().getNamespaceURI(prefix);
    }

    @Override
    public boolean hasText() {
        int eventType = getEventType();
        return eventType == XMLStreamConstants.SPACE || eventType == XMLStreamConstants.CHARACTERS
                || eventType == XMLStreamConstants.COMMENT || eventType == XMLStreamConstants.CDATA
                || eventType == XMLStreamConstants.ENTITY_REFERENCE;
    }

    @Override
    public String getPrefix() {
        int eventType = getEventType();
        if (eventType == XMLStreamConstants.START_ELEMENT || eventType == XMLStreamConstants.END_ELEMENT) {
            return getName().getPrefix();
        } else {
            throw new IllegalStateException("parser must be on START_ELEMENT or END_ELEMENT state");
        }
    }

    @Override
    public boolean hasName() {
        int eventType = getEventType();
        return eventType == XMLStreamConstants.START_ELEMENT || eventType == XMLStreamConstants.END_ELEMENT;
    }

    @Override
    public boolean isWhiteSpace() {
        return getEventType() == XMLStreamConstants.SPACE;
    }

    @Override
    public boolean isStartElement() {
        return getEventType() == XMLStreamConstants.START_ELEMENT;
    }

    @Override
    public boolean isEndElement() {
        return getEventType() == XMLStreamConstants.END_ELEMENT;
    }

    @Override
    public boolean isCharacters() {
        return getEventType() == XMLStreamConstants.CHARACTERS;
    }

    @Override
    public int nextTag() throws XMLStreamException {
        int eventType = next();
        while (eventType == XMLStreamConstants.CHARACTERS && isWhiteSpace()
                || eventType == XMLStreamConstants.CDATA && isWhiteSpace() || eventType == XMLStreamConstants.SPACE
                || eventType == XMLStreamConstants.PROCESSING_INSTRUCTION || eventType == XMLStreamConstants.COMMENT) {
            eventType = next();
        }
        if (eventType != XMLStreamConstants.START_ELEMENT
                && eventType != XMLStreamConstants.END_ELEMENT) { throw new XMLStreamException(
                        "expected start or end tag", getLocation()); }
        return eventType;
    }

    @Override
    public void require(int expectedType, String namespaceURI, String localName) throws XMLStreamException {
        int eventType = getEventType();
        if (eventType != expectedType) { throw new XMLStreamException(
                "Expected [" + expectedType + "] but read [" + eventType + "]"); }
    }

    @Override
    public String getAttributeValue(String namespaceURI, String localName) {
        for (int i = 0; i < getAttributeCount(); i++) {
            QName name = getAttributeName(i);
            if (name.getLocalPart().equals(localName) && (namespaceURI == null
                    || name.getNamespaceURI().equals(namespaceURI))) { return getAttributeValue(i); }
        }
        return null;
    }

    @Override
    public boolean hasNext() throws XMLStreamException {
        return getEventType() != END_DOCUMENT;
    }

    @Override
    public String getLocalName() {
        return getName().getLocalPart();
    }

    @Override
    public char[] getTextCharacters() {
        return getText().toCharArray();
    }

    @Override
    public int getTextCharacters(int sourceStart, char[] target, int targetStart, int length)
            throws XMLStreamException {
        char[] source = getTextCharacters();
        length = Math.min(length, source.length);
        System.arraycopy(source, sourceStart, target, targetStart, length);
        return length;
    }

    @Override
    public int getTextLength() {
        return getText().length();
    }
}
